Walking beam furnaces

ABSTRACT

A beam furnace comprises at least two main zones, one of which is for heating and the other for equalizing the temperatures of the charge elements. The beams of the first zone include charge supports which maintain the charge spaced from the furnace bottom and the beams of the second zone a bottom coating on which the charge rests directly.

United States Patent [72] Inventor Pierre Dcsarts [56] Reference Cited Pans France UNITED STATES PATENTS 5; g 33 1968 1,739,250 12/1929 Menne 263/6 1 e 2,039,203 4/1936 Ogilvy Webb... 263/6A [451 Patented 1971 3 373 980 3/1968 Bor kvist 263/6A [73] Assignee Societe Anonyme Heurtey q Paris, France Primary Examiner-John J. Camby [32] Priority Dec. 20, 1967 Attorney-Waters, Roditi, Schwartz & Nissen [33] France [31] No. 133,033

ABSTRACT: A beam furnace comprises at least two main [54] m} M FUFBNACES zones, one of which is for heating and the other for equalizing =rawmg the temperatures of the charge elements. The beams of the [52] U.S. Cl 263/6 first zone include charge supports which maintain the charge [51] Int. Cl F27b 9/14 spaced from the furnace bottom and the beams of the second [50] Field of Search 263/6, 6A zone a bottom coating on which the charge rests directlyv WALKING BEAM FURNACES It is customary practice to heat billets, blooms or slabs in walking beam fumaces prior to rolling, forging, or the like.

There are two well-known constructional forms for such furnaces. The first includes one .or more metal beams upon each of which rests acontinuous'bed of refractory products which support the charge as it moves along. These beams are inserted into one or more longitudinal grooves in the furnace hearth. The charge is caused to move forward by successive lifting, advancing, descending and retreating motions of said beams. I

The second constructional form includes metal beams, some stationary and others mobile, supported by columns which pass through a hearth of refractory products, the charge to be treated'being thus kept above the furnace-bottom at a level appropriate for ensuring heating of the upper and lower parts of the charge elements.

When temperatures are relatively low, particularly in the case of heatv treatments, the beams and their supporting columns may be made of refractory steel. For higher temperatures, as in the case of heating prior torolling, the columns must be cooled, for instance by internal water circulation, and the beams likewise consist of water-cooled tubes similar to those used in pusher furnacesl v With regard to heating of the furnace charge elements, in

the first type of furnace these have their top faces heated directly, their lateral faces heated partly, but their bottom faces not at all. I

In the second type of furnace the products have their top and bottom faces heated directly and their lateral faces more effectively than in the first type, though less directly. 7

As a result, heating in the second-type of furnace is much more rapid, resulting in shorter furnaces and more uniform temperatures of the individual charge elements since they are heated practically on all four faces. But such charge elements, which rest alternately on water-cooled walking beams and stationary beams, then exhibit black blemishes at the points of contact between the elements and'the beams, and due to a are necessarily of a size compatible with the longitudinal motion imparted as a result of the forwardand backward movements of the stringers and columns. In relatively low temperameans of drawer systems, but in the case of high temperature furnaces individual hydraulic seals are necessary and con-.

. stitute as many large cold spots; such seals are moreover soon shadowing effect these blemishes are surrounded by dark ZOHCS.

charge elements are rolled, and thisis manifestly a serious shortcoming of furnaces of the'second type. The present invention overcomes this drawback by providing a furnace in which the charge elements are heated, for instance up to the rolling temperature, in a section equipped with beams of the second type, while another section is associated with beams of the-first type andconstitutes a temperature equalization zone.

In this latter section of the primarily to maintain the surface of the charge element at the temperature required for rolling, and because this section is devoid of cooled members, the black blemishes or dark areas are heated therein by conduction from adjacent areas and laterally by radiation from the furnace, the transit therethrough being determined accordingly.

In a first form of embodiment of this invention, the furnace comprises at least one monobloc-type travelling beam with furriace,"heating may provided common actuating elements, which travelling and stationary whereasin prior art furnaces such columns are rigidly connected to a general frame located beneath a refractory hearth, and said columns traverse the latter'through openings which filled with oxides or like products dropping .off the charge elements undergoing treatment and cannot be cleaned conveniently. v I

The improved furnace according to the present invention offers the advantage of achieving sealing by a continuous hydraulic seal of conventional type which, as experience has demonstrated, due to the narrowness of the gap between the travelling'beams and the furnace bottom, will allow passage only of small amounts of oxides or other waste that can easily be eliminated from such seals, which seals furthermore do not constitute cold spots detrimental in particular to the quality of production.

The description which follows with reference to the accompanying nonlimitative exemplary drawings will give a clear understanding of how the invention can be carried into practice.

In the FIGS.:

FIG. 1 shows schematically, in longitudinal section along the line H of FIG. 2, a walking beam fumace of the kind disclosed.

FIG. 2 is a section through a horizontal plane taken along the line 11-11 of FIG. 1. 1 I

- FIG. 3 is asection on the line III-III of FIG. 2.

FIG. 4 is a section on the line IV-IV of FIG. 1.

FIG. 5 is a section on theline V-V of FIG. 1.

FIG. 6 is a section on the line VI-Vl of FIG. 1.

FIG. 7 is a view corresponding to FIG. 1, showing an alternative embodirnent with two independent beams.

In the embodiment shown in FIG. 1', the charge chamber 1 of a furnace is provided at its top with burners 2 and in its frontal walls with an opening 3 for insertion of the charge elements to be treated and an opening 4 for drawing these charge elements after treatment. Charge chamber 1 contains a hearth whose walking beam has mobile portions which rest on a metal member 5 capable of vertical and longitudinal motion.

To that end, as well known per se, the members 5 extend along the full lengthof charge chamber l and rest on sets of rollers 6 whose axles are carried on one end of rockingly mounted levers 7 whose other ends are interconnected by rods 8, one of these rods being connected to the power rod of a vertical hoisting jack 9. Members 5 are further connected to the power rod of a longitudinal advance jack l0..Thus it is possible to cause the members 5 to rise, to move longitudinally inthe without entrainingany charge elements during this ultimate phase of their motion.

The members 5 are provided along part of their length, on the side of charge insertion opening 3, with a refractory lining I 1. Along a complementary part of their length, on the side of charge drawing opening 4, the members 5 carry a step 12 supporting a refractory lining 13. A refractory wall 14 interconnects the two linings 11 and 13.

In the zone of lining 11, the uprights of charge chamber I bear burners l5. 7

Upstanding from refractory lining 11 are columns 16 which support stringers 17 forming extensions of the lining 13.

As FIGS. 2 and 3 clearly show, a walking beam of this kind is capable of cooperating with fixed hearth elements which flank it and include, in the region of the mobile stringers l7, fixed stringers 18 likewise supported by columns 19 and bearing against the uprights through the medium of spacers 20, while in the region of lining 13 the fixed hearth elements are provided with a refractory wall 21.

In order to ensure leaktightness, a rectangular liquid channel 22 is provided beneath the level of the members 5 and has dipping into it a sealing skirt formed with relatively low portions 23 in the area of lining 11 and taller portions 24. in the area of lining l3, and the tops of these skirt portions join leaktightly to said linings ll and'l3. Similarly, companion skirts 25 and 26 are provided at the periphery of the opening formed in the refractory coating .of the fixed hearth portions, the overall aim being to reduce to a minimum the gap between the fixed and mobile portions of the hearth.

Obviously, the width imparted to channel 22 is small in the longitudinal regions but fairly considerably in the transverse regions in order to permit playof the skirt sections 23 and 24.

therein. I

' The columns 16, the columns 19, the associated-spacers 20 and the stringers 17 and 18 are. hollow and may have .a cooling fluid flowing therethrough, for whichinlets. and outlets are provided, although not shown in the drawings. In the exemplary embodiment herein described, the furnace has twoidentical, parallel walking beams andfthree fixed hearth sections, whereby in the central section the columns 19 form thelegs of a gantry, and this likewise applied to the walking beam columns 16.

v From the mechanical standpoint, the manner of operation of this arrangement, as regards forward motionof the charge elements 27, is conventional, said elements being conveyed by the walking beams from one end. to the other of the fixed hearth portions, from inlet 3 to outlet 4, whence the elements are taken out by a conveyor 28. (shown only in highly schematic fashion in the drawings).

' On the stringers 17 and 1,8 the charge elements 27 are heated by burners 2 and on their, top andbottomsurfaces directly, and also on their sides, though less directly.

Those areas which have remained cool in contact with the stringers and in the adjacent regions are eliminated during the second part of the path followed .by the products, namely through the zone in which they reston therefrac'tory coatings l3 and 21.

Thus rapid heating is obtained-m the first-furnace zone and temperature equalization in the second.

As shown in FIG. 7, instead of a single walking beam running through the length of the furnace, such abearn could be constructed in two sections. in this alternative constructional form, a first member Sq supportslining 1 l, a wan, l4 and the associated stringers 17 by meansofthe columns 16.

A second beam with a raisedmember 5b supports the-coating 13 facing the top of wall 14. Each member 5a and S b comprises its own machinery, with hoisting and longitudinal motion jacks 9a, 100 and 9b, 10b. Withthis arrangementthe step 12 becomes superfluous, but it is preferably to providetwo independent and vertically staggered sealing channels 22a and 22b with associated skirts for each of members 5a, 5b.

These provisions have the added; advantage of enabling the products 27 to travel with differentspeeds and spacings to the heating and temperature equalization zones.

Other provisions well knownv in the beam. conveyor art could be associated with those hereinbefore.described suchas for example hearths and beams with stepped surfaces, or the possibility of varying the degree of hoistingso as to handle the products differently in certain zones in comparison with the other zones. Further, the beams could be devised so as to impart specific motions to the products, such as a rotation or a turning upside down thereof during their transport.

Manifestly also the number of treatment zones is by no means limited to two, and many othermodifications and substitutions of parts may be made in the specific embodiments described hereinabove without-department from the scope of the invention, as defined in the appended claims.

I claim:

1. Awalking beamfurnace comprising at least a first main heating zone for heating individual charge elements, a second main equalizing zone for equalizing the temperatures thereof, beams-in saidfirstzone including charge supports for keeping said charge elements spaced from a corresponding furnace bottom so that said elements are heated on the upper and lower surfaces thereof, and beams in said second zone includinga lining at the same level as the beams in the first zone for supporting said elements such that they rest directly on said lining so that the elements are directly heated on the upper surfaces thereof and temperature equalized on said lower surfaces by contactwith said lining, said charge elements being individually transferred through the furnace by direct and successive travel on said beams.

2. A furnace according to claim 1, in which said beams of said'two zones are rigidly interconnected.

3. A furnace according to claim 1, in which said beams of said two zones are independent of each other.

4. A furnace according to claim 1 in which said supports for maintaining said charge elements spaced from said furnace bottom comprise columns, and stringers supported on the columns, said columns and stringers including cooling means in which is circulated a cooling fluid.

5. A furnace according to claim 4 comprising a lining in said first zone on which said columns are fitted, means for moving said linings, in said first and second zones in grooves provided in stationary portions of the furnace bottom, and sealing meansbetween the linings and stationary portions including skirts dipping into a continuous hydraulic seal associated with said portions.

6 A furnace according to claim 1- comprising a lining in said first zone supporting said beams, said lining in said second zone being raised above the lining in said first zone, said charge supports comprising conveyor stringers in said first zone mounted on the lining therein and disposed substantially in the same plane as said lining in said second zone.

7. A furnace according to claim 6 wherein said linings are of refractory material.

8. A furnaceaccording to claim 7 comprising a refractory wall connecting said linings to form a step therebetween.

9. A furnace according to claim 7 wherein the furnace bottom-ineachzone is substantially coplanar with the associated lining therein,

10. A furnace according to claim 1 wherein said lining in said second zone is of refractory material. 

1. A walking beam furnace comprising at least a first main heating zone for heating individual charge elements, a second main equalizing zone for equalizing the temperatures thereof, beams in said first zone including charge supports for keeping said charge elements spaced from a corresponding furnace bottom so that said elements are heated on the upper and lower surfaces thereof, and beams in said second zone including a lining at the same level as the beams in the first zone for supporting said elements such that they rest directly on said lining so that the elements are directly heated on the upper surfaces thereof and temperature equalized on said lower surfaces by contact with said lining, said charge elements being individually transferred through the furnace by direct and successive travel on said beams.
 2. A furnace according to claim 1, in which said beams of said two zones are rigidly interconnected.
 3. A furnace according to claim 1, in which said beams of said two zones are independent of each other.
 4. A furnace according to claim 1, in which said supports for maintaining said charge elements spaced from said furnace bottom comprise columns, and stringers supported on the columns, said columns and stringers including cooling means in which is circulated a cooling fluid.
 5. A furnace according to claim 4 comprising a lining in said first zone on which said columns are fitted, means for moving said linings in said first and second zones in grooves provided in stationary portions of the furnace bottom, and sealing means between the linings and stationary portions including skirts dipping into a continuous hydraulic seal associated with said portions.
 6. A furnace according to claim 1 comprising a lining in said first zone supporting said beams, said lining in said second zone being raised above the lining in said first zone, said charge supports comprising conveyor stringers in said first zone mounted on the lining therein and disposed substantially in the same plane as said lining in said second zone.
 7. A furnace according to claim 6 wherein said linings are of refractory material.
 8. A furnace according to claim 7 comprising a refractory wall connecting said linings to form a step therebetween.
 9. A furnace according to claim 7 wherein the furnace bottom in each zone is substantially coplanar with the associated lining therein.
 10. A furnace according to claim 1 wherein said lining in said second zone is of refractory material. 